"Sandwich Thief" is the fourteenth episode of Season 2 of Teen Titans Go! and the sixty-sixth episode overall. It first aired on 25 September 2014 on Cartoon Network.
Someone steals Robin's perfect sandwich, and he's on the hunt to find it.
After passing security codes, including retina scanning and a floor-tile pattern (performed as a small jig), Robin heads to the laboratory to take his sandwich, only to find it missing. He finds the others at the living room, who doesn't notice where the sandwich is, even if it is legendary. Robin tells them it's not just any sandwich—it's the perfect sandwich. He had travelled to distant lands where he found the Sandwich Masters, who guided him in crafting it. After many tries—and not finding the perfect sandwich—he finally figured the secret to the one and only perfect sandwich, with a special mix of condiments. He then put it in a heavily-guarded refrigerator so that nobody could take it—but now, somehow, it's gone. Robin tells the others not to leave the room until he finds it, but the others ignore him.
First, Robin finds Cyborg, sitting on the bench. He hacks into his data to see if he ate his sandwich, but all he finds was that Cyborg at least once snuck into Robin's room to try on his pants. Starfire is shot by Robin later, and she finds herself inside a dark room, strapped to a lie detector. She gives truthful answers to every question, with the exception of a question about her feelings for Robin: when she is forced to confess that she does not return his affections, he leaves, dejected. Finally, Beast Boy starts to eat a taco next to Raven, but Robin slaps it out of his hands. He goes for a crime scene, and he goes inside him, but Raven should've have shrunk him first.
The others are not amused for Robin's actions, and Robin types in the computer for a few calculations, and finds the suspect who stole his sandwich: his future self. By using a time machine, the Titans are sent into the future.
Nightwing comes in, with groceries on his hands. Robin catches him, along with Raven and Starfire, and finds nothing in the fridge. Meanwhile, Cyborg and Beast Boy are in the time machine making crank calls out of boredom, but are interrupted when Beast Boy is informed that his future self passed away. Robin, Raven, and Starfire return, with no sandwich in sight. Robin decides to travel to another world by using a teleporter.
At a distant planet, Robin and the Teen Titans find the perfect sandwich, which, as Robin suggests, was made a little too perfect. The Titans find it, where its utter perfection caused it to become sentient and escape from Nightwing's fridge into space, whereupon it was enlightened into believing that the sandwich is the ultimate lifeform in the universe; thus, all other life must be exterminated. The Titans start to attack the sandwich, but it became powerful enough to generate its own force field and strike back. Robin suggests that it would only be eaten by its creator. As he fights back, he finally eats the sandwich, suggesting that it really is perfect.
Robin's sandwiches are called legendary again ("Legendary Sandwich").
Robin takes his sandwich-making skills by the Sandwich Masters. His ability to make sandwiches was mentioned in "Legendary Sandwich".
The other Titans are ignored by Robin's shenanigans, with the exception of Raven ("Dude Relax"). This time, Raven adds "no" as a result to finding Robin's perfect sandwich.
When Robin says he's traveled the world, the map depicts several DC references such as the location of the League of Shadows with a likeness of Ra's al Ghul and The Pit with a likeness of The Dark Knight Rises incarnation of Bane.
A poster depicts Superman and a saying of Be Super and Don't Litter.
Nightwing's room is filled with a poster of a chibi Batgirl and Terry McGinnis as Batman from Batman Beyond. His fridge is also filled with Batman-themed merchandise and Ivy hummus, referencing Poison Ivy.
The second sandwich master Robin trained with bears a resemblance to Afro from the anime and manga series, Afro Samurai.
Nightwing's doorbell is the same one from The Jetsons.
Beast Boy's Tyrannosaurus Rex roar is from Jurassic Park.
The floor-tile pattern Robin has to enter by way of dance to access his laboratory is likely a reference to the music video of Michael Jackson's "Billie Jean", which shows floor tiles lighting up as Jackson steps on them.
Nightwing does not live in the Titans Tower, nor does he have a wife. He instead lives in an apartment and lives alone in this episode, though he lives in the tower and is married with Batgirl in "Staring at the Future".
It could be an alternate future, or a point in the future before Nightwing married Batgirl.
Beast Boy starts to eat a taco despite being a vegetarian.
It was probably a taco with vegetable filling. He even points out that he is vegetarian to refute Robin's questions about him having eaten the sandwich.
The Image Gallery for Sandwich Thief may be viewed here.